Sabato says Trump will strike out in all of the so-called swing states, including Florida, Ohio and Virginia.

Four normally Republican states — Arizona, Georgia, Indiana and Missouri — could be less secure. The latter point is important because all four states have U.S. Senate races, and were Clinton to target them, it could help swing the results of the upper chamber as well.

The Wisconsin challenge for election 2016 front-runners

(1:36)

A new poll by Marquette University indicates the Wisconsin primaries may set the stage for a potential upset of both parties' front-runners.

That said, Sabato doesn’t expect the popular vote to be a landslide. “Instead of the winner topping 60% as in 1964 and 1972, it is more likely Clinton would garner less than 55% of the two-party vote,” he says.

He does pour cold water on the idea that blue-collar whites in Rust Belt states could make states like Michigan and Pennsylvania competitive. “There is little evidence that the non-college voters supporting Trump in the primaries are defectors from the Democrats; most have been backing GOP candidates fairly consistently, so the net addition for Trump could be small,” he writes.

Sabato also doesn’t think Sen. Ted Cruz as the nominee would improve the Republican chances very much. While Cruz nationally trails Clinton by less than Trump does — three or four percentage points — he may be an easier candidate to attack given his more vocal social conservatism, Sabato says. Also, he says, there’s the possibility that Trump supporters stay home if Cruz is the nominee.

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